GB2375062A

GB2375062A - Drill assembly with cutter arrangement and guide

Info

Publication number: GB2375062A
Application number: GB0202845A
Authority: GB
Inventors: David Larcombe Matthias
Original assignee: TECHNICAL SERVICES TEAM Ltd
Current assignee: TECHNICAL SERVICES TEAM Ltd
Priority date: 2001-10-27
Filing date: 2002-02-07
Publication date: 2002-11-06
Anticipated expiration: 2022-02-07
Also published as: GB2375062B; EA200400599A1; ZA200404119B; GB0202845D0; GB0125882D0

Abstract

A drill assembly 1 comprises a cutter arrangement 3 and a guide 2, 6 the guide having a longitudinal axis A-A. The arrangement of the assembly is such that, in use, the cutter arrangement engages with the guide and is caused to rotate about the longitudinal axis of the guide. The guide is shaped so as to move the cutter arrangement generally laterally of the longitudinal axis as the cutter arrangement moves in a direction which is generally parallel to said longitudinal axis. Preferably the guide has a frusto-conical profile so as to form a hole 20 of a corresponding shape. The drill assembly may be used in reaming pre-formed holes which are used to locate anchor bolts.

Description

DRILL ASSEMBLY The present invention relates to drill apparatus, and in particular, but not exclusively, to drill assemblies for creating holes suitable for receiving anchor bolts.

I It is known to install anchor bolts which are used to reinforce a structure, such as a bridge, by way of a tie between the fixed anchor bolt and the structure. Anchor bolts are also used in the fields of tunnelling and mining, and are used to secure masonry facings on buildings, and as high quality cavity wall tie replacement in brick and stonework.

In order to fix an anchor bolt a hole must be formed in which the bolt can be placed together with a filler such as grout. Various methods are known for producing such holes however all suffer from various disadvantages including lack of anchorage strength provided by the hole and the formation of a hole whose shape is not readily controllable.

The present invention seeks to provide an improved drill assembly.

According to one aspect of the invention there is provided a drill assembly comprising cutter means and guide means, the guide means comprising a longitudinal axis, the arrangement of the assembly being such that, in use, the cutter means engages with the guide means, and the cutter means being caused to rotate about the longitudinal axis of the guide means, and the guide means being shaped so as to move the cutter means generally laterally of the longitudinal axis as the cutter means moves in a direction which is generally parallel to said longitudinal axis.

Advantageously the guide means can be formed to a desired shape and in use the guide means will advantageously enable a hole of that shape to be accurately formed. In a preferred embodiment of the invention the guide means is shaped so as to cause the cutter means to produce a hole of variable diameter, and in particular, a flared pole.

Preferably the guide means comprises a generally elongate member which is adapted to be positioned in a pre-formed hole.

Preferably the guide means comprises a guide surface and in use the cutter means engages with the guide surface so as to determine the lateral movement of the cutter means.

The guide means preferably comprises a first substantially frusto-conical portion.

The guide means may comprise a second substantially frusto-conical portion, the direction in which the second frusto-conical portion tapers being opposite to that in which the first frusto-conical portion tapers.

The second substantially frusto-conical portion is desirably provided towards a distal end of the guide means.

Preferably the cutter means is resiliently biased against the guide means.

The drill assembly apparatus desirably comprises at least one cutter which is arranged for lateral movement in guide means. Preferably a plurality of cutters is provided. The cutters are desirably equally angularly spaced around the longitudinal axis.

In a preferred embodiment the apparatus comprises a housing which has formed therein a plurality of generally radially extending slots, and a central bore, a respective cutter being slidably mounted in each of the slots. The arrangement is such that a guide member extends through the central bore and in so doing the guide member engages with the cutters so as to control movement of said cutters in the slots.

The cutter means may be pivotally mounted for movement which is generally lateral of the longitudinal axis of the guide means. The cutter means may comprise a plurality of pivotally mounted cutters.

In a preferred embodiment a plurality of pivotally mounted cutters is arranged around the guide member. Advantageously such an arrangement provides a high degree of cutter surface coverage.

The cutter means may comprise a resilient limb, the resilient limb being generally laterally deflectable in response to the guide means.

The resilient limb may extend in a direction which is substantially parallel to the longitudinal axis. The resilient limb may be substantially helical.

A plurality of resilient limbs is desirably provided.

Preferably a cutting surface of the cutter means is substantially arcuate.

The guide means may comprise track means which locates the cutter means.

According to a second aspect of an invention there is provided a method of forming a hole comprising the steps of: inserting guide means into a pre-formed hole, the guide means comprising a longitudinal axis and comprising a variable diameter portion; arranging that cutter means engages with the guide means; causing the cutter means to rotate about the longitudinal axis of the guide means and causing the cutter means to move in a direction which is substantially parallel to said longitudinal axis.

According to a third aspect of the invention there is provided a drill cutter assembly comprising cutter means for engaging with guide means, the cutter means being adapted to rotate about a longitudinal axis of the guide means, and being adapted to move generally laterally of the longitudinal axis during engagement with said guide means.

According to a fourth aspect of the invention there is provided a drill cutter guide of generally elongate form comprising a longitudinal axis, and a guide portion which extends generally laterally of the longitudinal axis, and the drill cutter guide being adapted with a drill cutter assembly in accordance with the third aspect of the invention, the arrangement of the guide means being such that, in use, the drill cutter assembly engages with the guide portion and is caused to rotate about the longitudinal axis of the guide and, as the drill cutter assembly moves in a direction which is generally parallel to the longitudinal axis of guide means, the guide portion causes the cutter means to move substantially laterally of the longitudinal axis of the guide.

Various embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which :-

Figure 1 is a cross-sectional view of a first drill assembly in accordance with the invention ; , Figure 2 is an exploded view of the assembly shown in Figure 1 ; Figure 3 is a cross-sectional view on section 3-3 of the assembly shown in Figures 1 and 2, Figure 4 is an end view of the housing and one cutter block of the assembly shown in Figure 1; Figure 5 is a partial cross-sectional side elevation of that part of the assembly shown in Figure 4 mounted on a base plate; Figure 6 is a plan view of the base plate of that part of the housing shown in Figure 5; Figure 7 is an exploded plan view of a cutter block of the assembly shown in Figures 1 and 2; Figure 8 is an exploded side elevation of the cutter block shown in Figure 7; Figure 9 is a plan view of the cutter block shown in Figures 7 and 8; Figure 10 is a plan view of the cutter block shown in Figure 9;

Figure 11 is a plan view of a second cutter arrangement in which one cutter limb is shown in fully extended position; Figure 12 is a partial exploded plan view of the cutter arrangement shown in Figure 11 ; Figure 13 is a side elevation of the view shown in Figure 12; Figure 14 is a guide member for use in a further drill assembly in accordance with the invention ; Figure 15 is a drill housing for use with the guide member shown in Figure 14 ; Figures 16a to 16d show side elevations of snap shots the further drill assembly comprising the components shown in Figures 14 and 15 forming a hole; Figure 17 is an end-on view of the cutter housing shown in the condition in Figure 16a; Figure 18 is an end-on view of the cutter housing shown in Figure 16d ; Figure 19 is an alternative embodiment of the drill housing of Figure 15; and Figure 20 is a cross-sectional view of the cutter arrangement of yet a further drill assembly in accordance with the invention.

Figures 1 and 2 show a drill assembly 1 comprising guide means and a drill bit assembly comprising cutter means. The guide means comprises a guide member 2 of generally elongate construction having a longitudinal axis A-A and comprising an upper portion 5 and a lower portion 6., The upper portion 5 is of substantially cylindrical shape, and the lower portion 6 is of substantially frusto-conical shape. The lower portion 6 has a cone angle a given by tan-1 (1/100), which it has been found provides an optimum anchorage.

That distal end of the guide member 2 which is adjacent to the upper portion 5 is provided with a substantially circular washer 10, and that distal end of the guide member 2 which is adjacent to the lower portion 6 is provided with a substantially circular washer 11.

The cutter means comprises four equally angularly spaced cutter blocks 3 which are slidably mounted in radial slots 8, the slots 8 being formed in a lowermost end of a housing 9.

The housing 9 is of generally cylindrical tubular form, the uppermost end 14 of which is adapted to interface with drive means (not shown).

The lowermost end of the housing 9 comprises a central bore 22.

With reference in particular to Figures 3,4, 5,6, 7,8, 9 and 10, the cutter blocks 3 comprise a recess 29, a radially inner guide engagement face 15 and a radially outer cutter face 16. The cutter face 16 is provided by four arcuate portions 35a, 35b, 35c and 35d which are fixed to each cutter block. The portions 35b, 35c and 35d are provided with

cutter surfaces 35b', 35c'and 35d'respectively. The cutter surfaces are formed from diamond dust in a metal matrix.

With reference to Figure 5 (which shows only one cutter block), a hairspring 30 is located in the lowermost portion 17 of the housing 9.

An end 32 of the hairspring 30 is held captive in an annular recess 33 which is defined by the portion 17. The hairspring 30 comprises a finger 31 which resiliently engages with a wall 34 of the recess 29.

A base plate 40 is attached to the underside 39 of the portion 17. The base plate 40 is provided with a central aperture 41 and four radially outer apertures 42, the apertures 42 are aligned with the taped holes 26 of the portion 17 so that capscrews 43 (of which one is shown in Figure 5) may be fixed therethrough.

In use the assembly 1 operates as follows. The guide member 2 is initially lowered into a pre-formed hole of substantially constant diameter until the washer 11 sits on the base of the pre-formed hole. The uppermost end 14 of the housing 9 is then connected to drive means (not shown). Once activated the drive means causes the housing 9, and thus the cutter blocks 3, to rotate about the longitudinal axis A-A. In so doing the face 15 of each cutter block engages with the guide member 2. Initially as the housing moves generally downwardly, a hole of constant diameter is formed as determined by the upper portion 5 of the guide member which is of substantially cylindrical shape. As the housing moves progressively downwards the faces 15 of the blocks will eventually engage with the lower portion 6 of the guide member 2 and which results in the cutter blocks being urged progressively laterally of the axis A-A. The hairsprings 30 ensure that the blocks are urged against the guide member at all times. A substantially frusto-conical recess 20 is thus formed.

Figure 11 shows an alternative cutter arrangement 50 comprising five equally angularly spaced cutter limbs 51 which are mounted for pivotal movement. The arrangement 50 is located at a distal end portion 55 of a housing similar to that of assembly 1.

I Each cutter limb 51 comprises an arcuate cutter face which comprises two arcuate cutter portions 57a and 57b made of suitably hardened material. Each limb 51 further comprises an abutment portion 56, a guide engagement portion 58, a first curved portion 60, a second curved portion 61 and a third curved portion 62.

The limbs 51 are sandwiched between a lower plate 53 and an upper plate 64. The lower plate 53 is of generally annular shape and is provided with five equally angularly spaced holes 65 and a central aperture 66. The upper plate 64, which is fixed to the lowermost portion 55, is also of generally annular shape and is provided with five equally angularly spaced holes 67 and a central aperture 68.

In an assembled state five capscrews comprising a head 69 and a pin 71 are passed through aligned holes 65 and 67 and through pivot holes 70 of each of the limbs 51.

A spring 72 is located by each of the capscrews, the spring 72 comprising two arms 74 and 75. The arm 74 is arranged to bear against an inner surface 76 of the lower plate 53 and the arm 75 is arranged to bear against the third curved portion 62 of each respective limb 51.

The cutter arrangement 50 operates as follows. A guide member identical to that of assembly 1 is lowered into a pre-formed hole of substantially constant diameter. As the arrangement 50 is caused to rotate about the longitudinal axis of the guide member, the guide

engagement portions 58 of the cutter limbs 51 engage with the guide member and as the cutter arrangement moves progressively downwards into the pre-formed hole the guide member causes the limbs to pivot generally laterally of the longitudinal axis about an axis which is defined by each of the capscrews 69 and forms a, reamed hole 78. As the limbs 51 move progressively laterally outwards, different portions of the cutter portions 57a and 57b come into contact with the material which is drilled.

The cutter surfaces 35b', 35c'and 35d'of each cutter block gradually wear away through use and in so doing expose fresh cutting surfaces until eventually no cutting material remains and the cutter blocks need to be replaced.

With reference now to Figures 14,15, 16a-16d, 17 and 18, another drill assembly 80 comprises a guide member 81 and a housing 82. The guide member 81 comprises an upper portion 83, a flared portion 84, a tapered portion 85 and a lower portion 86. The guide member 80 is provided at its uppermost end with an end portion 87 and at its lowermost end with a nose portion 88. The flared portion 84 and the tapered portions 85 are both of substantially frusto-conical shape, with the cone angle of the portion 84 being given by tan' (1/100), and the cone angle of the portion 85 being greater than that of the portion 84.

The housing 82 is of substantially tubular form and comprises two resilient limbs 90, and is provided with two generally longitudinally extending apertures 89, at a distal end of which there is provided a crosshole 95.

Each limb is provided with a cutter portion 91 of substantially arcuate shape which is formed from hardened material.

On a radially inner surface of each limb there is provided a guide engagement portion 92.

f In use the assembly 80 operates as follows. The guide member 81 is initially lowered into a pre-formed hole. The housing 82 is then caused to rotate about the longitudinal axis of the guide member and engage therewith.

As can be seen from Figures 16a to 16c, the guide engagement portions 92 engage with the guide member, and the flared portion 84 causes the limbs 90 to progressively deflect generally laterally of the longitudinal axis of the guide member 82 as the housing moves downwards. The tapered portion 85 causes the limbs to be deflected laterally inwardly until, finally, the guide engagement portions 92 engage with the lower portion 86. In such a condition the assembly 80 can then be withdrawn from the reamed hole 98.

Figure 19 shows an alternative embodiment similar to the assembly 80, but comprising a housing 82'. The housing 82'comprises two substantially helical resilient limbs 90'which are defined by two substantially helical apertures 89', at a distal end of each there is provided a cross-hole 95'. The housing 82'further comprises two cutter portions 91'which are provided on each limb 90'.

Turning to Figure 20, there is shown a cutter arrangement 100 of yet a further embodiment of the invention.

The cutter arrangement 100 comprises a guide member 102 which is identical to the guide member 2 except that the member 102 is provided with four tracks 105 which each define four slots 110 which extend along the length of the guide member 102. Each track 105 locates a cutter block 101 which comprises a radially outer c, utter face 106 and a radially inner abutment 107. Each cutter block 111 further comprises two shoulders 108 which engage with two complementary surfaces of each of the tracks 105.

The blocks 101 are arranged to be slidably mounted in radial slots 111 which are provided in a housing 112.

In use the housing 112, the cutter blocks 101 and the guide member 102 is caused to rotate and in so doing as the cutter blocks move progressively further into a pre-formed hole the blocks 101 move laterally outwardly in the slots 111 in accordance with the shape of the guide member 102, and thus form a reamed hole 115.

Although the guide members of the various embodiments hereinbefore described comprise a substantially frusto-conical portion, a guide member in accordance with the present invention may comprise a portion which curves outwardly to produce what may be termed as a'bell-shape'so as, in use, to cause lateral movement of the cutter means.

It will be appreciated that a guide member may comprise a plurality of adjacent frusto-conical portions tapering in the same direction.

Claims

CLAIMS 1. A drill assembly comprising cutter means and guide means, the

guide means comprising a longitudinal axis, the arrangement of the assembly being such that, in use, the cutter means engages with the guide f means, and the cutter means being caused to rotate about the longitudinal axis of the guide means, and the guide means being shaped so as to move the cutter means generally laterally of the longitudinal axis as the cutter means moves in a direction which is generally parallel to said longitudinal axis.
2. A drill assembly as claimed in claim 1 in which the guide means comprises a generally elongate member which is adapted to be positioned in a pre-formed hole.
3. A drill assembly as claimed in claim 1 or claim 2 in which the guide means comprises a guide surface and in use the cutter means engages with the guide surface so as to determine the lateral movement of the cutter means.
4. A drill assembly as claimed in claim 1, claim 2 or claim 3 in which the guide means comprises a first substantially frusto-conical portion.
5. A drill assembly as claimed in claim 4 in which the guide means comprises a second substantially frusto-conical portion, the direction in which the second frusto-conical portion tapers being opposed to that in which the first frusto-conical portion tapers.
6. A drill assembly as claimed in claim 5 in which the second substantially frusto-conical portion is provided towards a distal end of the guide means.

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7. A drill assembly as claimed in any preceding claim in which the cutter means is resiliently biased against the guide means.
8. A drill assembly as claimed in any preceding claim which comprises at least one cutter which is arranged lateral movement in guide means.
9. A drill assembly as claimed in claim 8 which comprises a plurality of cutters.
10. A drill assembly as claimed in claim 8 or claim 9 which comprises a housing which has formed therein a plurality of generally radially extending slots, and a central bore, a respective cutter being slidably mounted in each of the slots.
11. A drill assembly as claimed in claim 1 in which the cutter means is pivotally mounted for movement which is generally lateral of the longitudinal axis of the guide means.
12. A drill assembly as claimed in claim 11 in which the cutter means comprises a plurality of pivotally mounted cutters.
13. A drill assembly as claimed in claim 1 in which the cutter means comprises a resilient limb, the resilient limb being generally laterally deflectable in response to the guide means.
14. A drill assembly as claimed in claim 13 in which the resilient limb extends in a direction which is substantially parallel to the longitudinal axis.

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15. A drill cutter assembly substantially as described and shown in the accompanying drawings.

15. A drill assembly as claimed in claim 1 in which the guide means comprises track means which locates the cutter means.

16. A method of forming a hole comprising the steps of : f inserting guide means into a pre-formed hole, the guide means comprising a longitudinal axis and comprising a variable diameter portion; arranging that cutter means engages with the guide means; causing the cutter means to rotate about the longitudinal axis of the guide means and causing the cutter means to move in a direction which is substantially parallel to said longitudinal axis.

17. A drill cutter assembly comprising cutter means for engaging with guide means, the cutter means being adapted to rotate about a longitudinal axis of the guide means, and being adapted to move generally laterally of the longitudinal axis during engagement with said guide means.

18. A drill cutter guide of generally elongate form comprising a longitudinal axis, a guide portion which extends generally laterally of the longitudinal axis, and the drill cutter guide being adapted to engage with a drill cutter assembly of claim 17, the arrangement of the guide being such that, in use, the drill bit engages with the guide portion and is caused to rotate about the longitudinal axis of the guide and, as the drill cutter assembly moves in a direction which is generally parallel to the longitudinal axis of guide means, the guide portion causes the cutter means to move substantially laterally of the longitudinal axis of the guide.

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19. A drill assembly substantially as described and shown in the accompanying drawings.

20. A method of forming a hole substantially as described and shown in the accompanying drawings.

21. A drill cutter assembly substantially as described and shown in the accompanying drawings.

22. A drill cutter guide substantially as described and shown in the accompanying drawings.

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Amendments to the claims have been filed as follows CLAIMS

1. A drill assembly comprising cutter means and guide means, the guide means comprising a longitudinal axis, the cutter means being mounted for pivotal movement which is generally lateral of the longitudinal axis of the guide means about respective pivot axes which are substantially parallel to the longitudinal axis of the guide means, the arrangement of the assembly being such that, in use, the cutter means engages with the guide means, and the cutter means being caused to rotate about the longitudinal axis of the guide means, and the guide means being shaped so as to move the cutter means generally laterally of the longitudinal axis and the cutter means having a component of movement in a direction which is generally parallel to said longitudinal axis.

2. A drill assembly as claimed in claim 1 in which the guide means comprises a generally elongate member which is adapted to be positioned in a pre-formed hole.

3. A drill assembly as claimed in claim 1 or claim 2 in which the guide means comprises a guide surface and in use the cutter means engages with the guide surface so as to determine the lateral movement of the cutter means.

4. A drill assembly as claimed in claim 1, claim 2 or claim 3 in which the guide means comprises a first substantially frusto-conical portion.

5. A drill assembly as claimed in claim 4 in which the guide means comprises a second substantially frusto-conical portion, the direction in which the second frusto-conical portion tapers being opposed to that in which the first frusto-conical portion tapers.

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6. A drill assembly as claimed in claim 5 in which the second substantially frusto-conical portion is provided towards a distal end of the guide means.

7. A drill assembly as claimed in any preceding claim in which the

cutter means is resilientiv biased against the guide means.

Z7 8. A drill assembly as claimed in any preceding claim in which the cutter means comprises a plurality of pivotally mounted cutters.

9. A drill assembly as claimed in any preceding claim in which the cutter means comprises a substantially arcuate cutter surface.

10 A drill assembly as claimed in any preceding claim in which the cuttermeanscomprisesacuttersurfacewhichisformedfromdiamond dust in a metal matrix.

] 1. A method of forming a hole comprising the steps of : inserting guide means into a pre-formed hole, the guide means comprising a longitudinal axis and comprising a variable diameter portion, arranging that cutter means engages with the guide means ; causing the cutter means to rotate about the longitudinal axis of the guide means and to have a component of movement in a direction which is substantially parallel to said longitudinal axis and causing the cutter means to move generally laterally of the longitudinal axis about the pivot axes which are substantially parallel to the longitudinal axis.

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12. A drill cutter assembly comprising cutter means for engaging with guide means, the cutter means being adapted to rotate about a longitudinal axis of the guide means, and being adapted to move generally laterally of the longitudinal axis about pivot axes which are substantially parallel to the longitudinal axis as a result of engagement with an outer surface of said guide means.

13. A drill assembly substantially as described and shown in the accompanying drawings.

14. A method of forming a hole substantially as described and shown in the accompanying drawings.